Analysis of Escherichia coli Isolated from Patients Affected by Crohn’s Disease

Abstract

The etiopathogenesis of Crohn's disease (CD) is still controversial: several genetic, immunologic, and environmental factors, including some bacteria, have been implicated. This study has been devised to assess the involvement of Escherichia coli in CD. Seven E. coli strains were isolated from 14 biopsies obtained from ileocolic ulcers of patients affected by inflammatory bowel disease (IBD), including six with ulcerative colitis and eight with CD. Five strains, exclusively isolated from CD patients, were found inside mucosal cells. Different PCR techniques (for chuA, yjaA, TspE4.C2, escV, and bfpB genes) were performed and PFGE was carried out to characterize these bacteria in comparison with other E. coli strains isolated from non-IBD specimens. The correlation of these characters with bacterial invasiveness on intestinal (Caco-2) and phagocytic (U937) cells was assessed. Overall our pilot data suggest that five among eight strains isolated from CD patients belonged to the adherent-invasive E. coli (AIEC) group, and were invasive on Caco-2 cells and resistant to phagocytosis. These findings suggest that these bacteria could be considered target organisms whose elimination could reduce the intestinal inflammatory process and CD progression.

Prevalence of Adherent-Invasive Escherichia coli with fimH Gene Isolated from Iranian Patients with Ulcerative Colitis

“…In this regard, Raso et al reported that AIEC was not detected in patients with UC and control subjects (27) and likewise, other studies found a higher prevalence for fimbriae I, encoded by the gene fimA, in UC patients compared to healthy individuals (28,29). However, in our study, 56.7% of the patients with UC were positive for AIEC, in particular for those with fimHgen; a rate that was significantly higher than the rates reported by previous studies.…”

Increased S-Nitrosylation and Proteasomal Degradation of Caspase-3 during Infection Contribute to the Persistence of Adherent Invasive Escherichia coli (AIEC) in Immune Cells

“…AIEC are six times more likely to be isolated from ileal samples of CD patients compared to controls and in intestinal lesions from CD patients E. coli strains represented from 50 to 100% of the total bacteria present [1], [5]. Further to this, AIEC isolated from lesions of CD patients are capable of invading epithelial cells and resisting phagocytosis [6]. While the idea of a single bacterial causative agent in CD remains controversial, the majority of host genetic mutations implicated in the disease are linked to autophagy, a programmed cell death (PCD) pathway intrinsically linked to the removal of intracellular bacterial pathogens [7], [8], [9].…”

Pathogenesis of Human Enterovirulent Bacteria: Lessons from Cultured, Fully Differentiated Human Colon Cancer Cell Lines

“…It has been hypothesized that the LF82 genome has evolved from those of extraintestinal pathogenic E. coli (ExPEC) B2 strains by the acquisition of Salmonella and Yersinia isolated or clustered genes or predicted coding sequences located on plasmids and at various loci on the chromosome (441). Following the isolation of the prototype AIEC LF-82 strain, other CD-and UC-associated AIEC strains have been isolated and characterized (442)(443)(444)(445)(446)(447)(448)(449). The results indicate that AIEC isolated from IBD patients has not evolved from a single ancestral background but corresponds to a group of bacteria that have been able to take advantage of an "IBD microenvironment" and probably share some common genes with ExPEC (446).…”